Photoelectric control mechanism for flame-cutting devices



Marcia M9 il W. s. FANDLER En m.

` y kPHCYIOELECTRXC CONTROL MECHNISM FOR FLAME-CUTTING DEVICES Filed oct. s, 1942 6 Sheets-Sheet l mm mm bv. NJ

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March 16, 1948. w. s. TANDLER Er AL 2,438,098

PHOTOELECTEIC CONTROL HECHANISH FOR FLAME-CUTTING DEVICESl Filed oct. s, 1942 s sheets-sheet s FIGBB.

INVENTORS. WILLIAM S. TANDLER 8- DAVID S. WALKER.

THE l2 ATTOENE YS.

March 16, 1948.

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WILLIAM S TANDLER and DAVID S WALKER;

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PHQTOELECTRIC CONTROL IECHANISII FOR FLAME-CUTTING DEVICES INDE Patented Mar. 1'6, 1948 PHOTOELECTRIC CONTROL MECHANISM FOR FLAME-CUTTING DEVECES William S. Tandler and David S. Walker, New York, N. Y.,'assiznors, by mesne assignments,

to Reconstruction Finance Corporation, New

York, N. Y., a corporation oi' the United States Application Getallen 95 i942, Serial No. 461,404

This invention relates to photo-electric devices for use lo the automatic control oi manufactus= ing operations and relates more particularly to photo-electric cell devices for automatically coun trolling the operation of machining or cutting de vices such as, for example, oxyacetylene torches ol other Aflame-cutting devices.

Many industries use cutting torches lor cutting out articles of complex outlines from metal, lor example, in the ship-building art steel plates are out into complex shapes in order to fit togethel: to form the hull, bulkheads, decks, etc., of ships. liu this art it has been customary to construct a @Museale-template or pattern for each part .tem quired, and then to punch-merli a steel sheet with the veduii'ed outline through the template. it cuttlhg torch is there manually guided over meules to out out the outlined article.,

This type oi operation is not entirely catalase tcy Aloi* the reasons that production yates low and a high degree of skill is required te ma@ nipulate the cutting torch accurately. The tern must los laid out on each sheet, thei'ehy cause liucn considerable delay in producing a finished article. Other errors and delays arise during the cutting operation., The high llame intensity of the cutting torch necessitates the use ci oasis cobalt glasses for the workmen. so that the punchl maries ase dlmcultto see.. es a result, the cutting operation must he stopped from time to time in cider to checl the accuracy ci the cut being the le, Moreover, the template is usually made heavy papes, wood or the like and, there-foie, is Yrlilcult to produce, transport and store without damage.

in order to overcome the disadvantages ci liteit-= ual damewuttine, it has been suggested pantogiaph device be prolided to guide the torch. .il template, in the nature of a duplicate ci the article heine produced, is used to control the sito tion ci the torch. While such a pantogsaph mechanism is an improvement over manual opeeation of a torch, it leaves much to be desired from the staudpoints of accuracy, speed in cuttingf and versatility in the cutting of various shapes.

Inasmuch as the pantograph mechanism le guided hy the template, the template is subject to weer with a resulting loss of accuracy, Move= over, the template must be fixed in position with relation to the pantograph and the metal being cut must also be disposed in a predetermined re lationship to the torch and template in order to assure movement of the torch over the metal. The templates, being of the same size as the artl= cle being produced. take up a considerable amount i, directions -by means ci a ileuilole tape and el space, especially when large plates are being cut, and thus a proportionately larger area loe set aside los location ci the name-cutting device. llicst importantly, the manufacture and replacement ci the template is dlfllcult and thus the prior devices are limited ic their capacity to produce readily a wide variety of diil'ereutly shaped azticles.

hn object ci' the invention is to provide appara tus which is adapted to execute automatically any desired outline.

mother object ci the present invention le to provide flame-cutting apparatus which may ice automatically controlled to out metal inte sulla stantially any desired shape without manual aum peivlsioh or control without the use of templatesa Another object oil present invention is to provide :llame-cutting appaiatus which may controlled hy means of ah easily and simply made permanent recotcl that can he used indefinitely for duplication of the saine pattern, without ectihg the accuracy of the record.

Still another object of the present invention is to piovide improved apparatus 160;" automatically tracing any desired outline or curve hy means ci two motois producing right singularly related.

components o motion to move a tracing mehohes along an outline, seid motors come controlled. oy photo-electrlc cells and e. record system tot che?a gioia' cells.

additional obiect ci ti c iuveutiou is f l tide a mechanism. foi: translaticnally movin index or tracing member in. iclvvaid and ievez'se the control ci? a motor or other motive dev While maintaining full synchronism between rote lou @i the motel1 and the motion ci? i. menthe?.

@thee objects and. advantages of the pzeseut invention will become apparent ,tromv the follow los" description ci a typical torno oi device em bullying the present invention.

Fcl purposes of illustration the invention will he described as embodied in a llame-cutting de vice, although it le not limited to such devices.

Eh accordance with the present invention, e. cute time torch is moved along perpendicular paths lay means of a pair oi motors that are controlled hy photo-electric cells. The photo-electric cells er@ energizeci` os deenerglzed by means oi suitable charia lor example, in the form of drums, to control the operation ol the motors which move the torch.

More particularly, the device may include a 3 carriage for a cutting torch which is mounted upon a rail or boom for movement in a straight line along the boom. A second perpendicular component of motion is obtained by moving the entire boom at right angles to the path of movement of the carriage along the boom so that the torch canv be moved in any combination of straight or curved lines, as desired.

As a practical matter, it is not possible to cause the torch to traverse accurately a variety of curved or inclined paths of predetermined curvature or incline by means of a pair of motors, for the reason that the speeds of the motors cannot be controlled within sufficiently close limits to maintain the necessary relationship between the two components of motion.

The present invention, therefore, includes mechanisms which cause the motors to operate alternately and thereby cause the torch to traverse a zig-zag path closely corresponding to the desired curvature or incline. Actually, when the torch is moved in short steps in such a zig-zag path, it fuses the serrations so that a substantially smooth edge is produced.

Precise control of the motion of the torch in such a zig-,zag path is obtained by rendering the operation of the motors and the control mechanisms dependent upon each other. Thus the control mechanisms are so arranged that .one motor is stopped after the torch has moved a predetermined distance and operation of the other motor is initiated. In this way an extremely close relationship between the operation of the motors and the movements of the torch is maintained at all times. p

The motors for moving the torch are started and stopped by means of a photo-electric cell system including a pair of control records such as, for example, hollow cylindrical drums provided with index markings.

Precise control of the operation of the motors and displacement of the torch is obtained for the reason that the drum actuated by one motor controls the operation of the other motor. In this way, the control drums for the respective motors are directly related to the movement of the torch and assure that each movement of the torch is related to the immediately preceding motion.

The control record may be easily made in accordance with the present invention by initially tracing a desired outline on a drawing or pattern once and applying markings to the drum at the various points at which one motor is stopped and the other is started. When the Various control points have been marked upon the drums and the drums setin their starting position, the motors may be operated by the drums to cause the torch to retrace the pattern. The torch will advance in a given direction until the control point or marking on the drum is sensed by a photoelectric cell, at which time the motor then operating will be stopped and the motor for driving the torch at right angles will begin to operate, thus advancing the torch at right angles to the initial cut. This cutting operation will proceed until a second control point on a drum passes a photo-electric cell at which time the motor then operating will be stopped and the other motor will be energized.

Apparatus of the type described generally above does not require a template for guiding the cutting torch and, therefore, the apparatus can be shifted from place to place. Thus the boom and control mechanism maybe mounted upon rails and can be moved into position to cut one plate while a second plate is being moved into position at a different place to be cut subsequently. The device then may be shifted to cut the second plate while the previously cut plate is removed and replaced with an additional plate to be operated upon by the cutting device.

When cutting plates of large dimensions, it has been found that nearly as much time is required to remove the cut plate and replace it with another plate asis required in the cutting operation, It will be apparent that the ability of the cutting device to be shifted from place to place results in a marked increase in output. Moreover, the.

device can be equipped with a plurality of torchesv so that two or more plates can be cut simultaneously without making the device excessively large.

The charts or drums for controlling operation of the motors are not in engagement with any relatively moving parts and thus are not subject to wear. Therefore, they can be used indefinitely for reproducing a desired pattern. However, the device is arranged to permit ready removal and replacement of the drums so that the device can be changed quickly to out different patterns. Moreover, inasmuch as the device may be provided 'with mechanism for applying index markings tothe drums by merely tracing the outline of an original pattern, new control drums can be prepared easily for simple drawings. r.he size of the drawings is of little importance, inasmuch as the device can be adjusted to make control drums for full-scale operations from fractional scale drawings.

For a better understanding of the present invention, reference may be had to the following description of the drawings illustrating a typical embodiment of the invention in which:

Figure 1 shows a plan View of the present invention;

Figure 2 shows a longitudinal elevational view of the device of Figure l;

l Figure 3 shows a p lan View of the lateral torch drive of Figs. 1 and 2 more in detail;

Figure 4 shows a cross-section of Fig. 3 taken along line fl-;

Figure 5 shows a diagram of a representative outline to be traced, useful in explaining the operation of the device;

Figures 6 and 7 show developed views of representative control records .for producing the outline of Fig. 5,

Figures 8A, 8B and 8C show a. complete schematic wiring diagram for controlling the cutter; and

Figure 9 shows a schematic wiring diagram for controlling the system during the making of the control record.

Figures 1 to 3 show the structure of the device of the present invention. A flame cutting torch or other cutting device i i is supplied with the gases whose combustion provides the high temperature cutting name by way of suitable tubing l2 from pressure cylinders or other sources, not shown. Torch li is carried by a carriage i 5 sliding on a, xed boom or arm il, and is adapted to be moved laterally with respect to the'steel plate or other work being cut, by connection to a flexible steel tape i3 which is continuously wrapped about a pair of drum pulleys i Il, I6 rotatably xed at either end of arm il by means-'of suitable brackets yand bearings i8, i9. Pulley i4, and hence torch il, is driven from a suitable electric motor 26 through reduction gearing 2l, 22, in the manner shown in Figs. 3 and 4, described be low'. Accordingly, torch I I is continuously moved laterallyso long as motor rotates, and at a rate proportional to the speed ol motor 20. Motor 20 is preferably but not necessarily chosen to be a constant speed motor, such as of the threephase induction type. and torch Il will be moved by an amount proportional to the angular rotation of motor 20 and in a direction corresponding to the sense of rotation of motor 20. A plugging switch 25, for controlling stopping oi motor 20 as will be described, is also driven from motor 20.

Also driven from motor 20, as 'by being coupled to a gear box 22 through further gearing 23 and an electromagnetically operated reversing clutch 24, is a control drum or cylinder 26 Aadapted to carry helical control records 2l, 28, 29 which control the operation of torch il in the manner to be described below. In this way drum 28 and its control records are rotated synchronously and proportionately to the rotation of motor 20 and the motion of torch il. Clutch 2d is adapted to reverse the relative directions of rotation of drum 26 and motor 2d, according as one or the other of its two control solenoids (not shown) are energized, as will be described. When xboth solenoids are energized, the drum lit is disengaged from motor 2li. Clutch 2li may be of any suitable type well-known in the art and 6 55, 56 similar to records 21, 28, 29 of drum 28, which cooperate with scanners 5l, 58, 59 mounted on a travelling support 50 similar to 45 to yield respective control signals which are led to control box 4| by cables 6I, 62, 63. Also connected to control box 4I, as by cables 64, 66, are the motors 46 and 2U, which are thereby controlled is fixed at one end to drum i4 as lby a pin or its details form no part of the present invention.

Cooperating with each of the records 2l, 28, of drum 25 is a corresponding 'photoelectric scanner, comprising respective light sources 3i, 32, 33 each adapted to project a narrowpencil or ray oi light upon its corresponding record, to be reiiected therefrom into respective photoelectric cells 3d, 35, 3b, which sense the presence of light-reflecting marks on the records, and con vert them into corresponding current impulses which are led .by cables 3l, 3i), 39 to an amplifier and relay control box di, whose circuit is shown more in detail in Figures 8A and SB. These scanners are translated longitudinally of drum 263 in synchronism with the rotation thereof, as by a suitable screw shaft and travelling nut arrangement @l5 driven together with drum 25 irorn motor 2li, whereby each scanner executes a heli1 cal path relative to drum 26, along which path the presence or absence of reflecting marks form the control records mentioned above. The drum is preieralbly made or" black material and `the control marlss oi light-reilecting substance, such as aluminum paint.

For providing longitudinal movement or" the torch ii, the entire apparatus thus far described is mounted on a carriage or moving platform l2 provided with wheels or rollers d3 cooperating with iixed rails dil, whereby carriage l2 may be readily moved along rails lill. The motive power for carriage l2 is provided 'by a second motor it mountedon carriage 2, which drives a pinion 4l engaging a fixed rack or cog=rall lil through suitable reduction gearing 49. Accordingly, the energizaton of motor llt will produce rotation of pinion 4l andA will drive motor lb and carriage l2 along rails 44 and cog-rail i8. A plugging switch is also driven from motor 'A second control drum 5l is also provided, driven in synchronism with motor l and the movement of carriage 42 (and hence with the longitudinal motion of torch il), as by means ci a pinion 52 engaging rack 48. Accordingly, as carriage 42 moves along rack 48, pinion 52 is rotated, thereby rotating drum5| throughareversing clutch 53 similar to clutch 2li.Y Drum 5i is also provided with three photoelectric records 54,

Sil

ing means 86.

bolt 8i, and is wrapped therearound in the form of a helix d2. In'order for the tape to remain fiat on the drum, it is necessary that it yiorrn a small acute angle -With a normal to the drum as it unrolls from the drum. This angle is shown greatly exaggerated in the figure, and is actually very small, of the order of about one degree. For this reason, the arm or boom il is disposed at an acute angle with respect to the axis oi ron tation of drum lll. Preferably, boom i'l is per pendicular to the'direction of motion of carriage 12, so that the axis of rotation of drum ill is necessarily not along this direction. The tape ifi is fixed, as will be described, 'to the sliding block. or carriage i5, which is guided along arm l'l by suitable flanges "l, as shown more clearly in Fig. 4, or by any other 'suitable means: Rollers may be provided to facilitate the movement oi carriage it.

Another section lila oi tape i3 is fastened to the other end'of the sliding block lll, as will be described, and extends therefrom over the idler drum it, and thence bach to the drum lflyto which it is also fastened, es 'by suitable fasten@ Drum il :may be rnade in two separate sections ifi, lila, as shown, rigidly fixed together. Tape i3 is :made to lle 'fully dat on each of the drums.

It will be clear that as drum l turns, one end oi the tape i3 will be wrapped around drum it, and the other end will be unwrapped from the drum. in the position shown in iuu lines in Fig. 3, the slide block iti is at the irl-most position, and the right part of the drum ill is fully wrapped by the tape, while the left end idc; is fully unwrapped. in the extreme outrnost position or the slide block i5, as shown in dotted lines, the tape will be fully unwrapped from the right part of drum ill and wrapped upon the leit part lila. in so doing, however', it will be seen that the tape must more to the right with respect to arm i3, in order not to slip with respect to the drum, which slipping would throw the torch il and record drum 26 out of register, and would irnpair the accuracy and usefulness of the appara tus. To permit this side motion, the points of connection of the tape i3, i3d 'to the slide bloei; l5 are not hired to the bloeit iii, butare made movable with respect thereto, as by means of auxiliary slides 8l and Se slidably mounted on respective slide rails 8s and @t lxecl to slide block i5 transversely of arm il. In this manner it is assured that the force applied to the torch-z carrying slide block I5 will always be in the direction of desired motion of the torch, exactly along arm Il,l thereby producing an easy and aandoen accurate control of the lateral motion of the torch li within narrow limits or variation.

To further assure that the tape it always aligns itself along the arm il, the auxiliary slide blocks El and to are provided with projecting pins on the lower sides thereof, one ci which,I ill, is shown in Figa. These pins are guided by a guide groove Q2 xed to the arm il, so that as the tape i3 unwinds from the drive drum i@ and the' slide block moves along arm il, the guide groove 92 forces the pins 9i and hence the auxiliary slide blocks Bl, S8, laterally with respect to the arm il, in the proper proportion to maintain the tape i3 in the desired alignment along arm il at all times. Lt will be clear that for this purpose guide groove 82 must extend perpendicular to the axis of drum lil, and the pins el must be oset from the tapefastening points in opposite senses to cooperate with groove 92.

The manner in which the present system operates may best be explained by reference to the diagram of Figure 5, in which arrow @t indicates the direction of longitudinal motion or' torch il,

shown. As will be described, the A and B motors operate alternately, one stopping as the other starts.

If it be desired that` the torch nl execute or trace the outline lVI-N-P-Q-R-M of Fig. 5, starting from point M, then along M-N, only the A motor need operate, to trace the required outline. Let it be assumed that the A-drum records 5t, 55, 5S are at position m relative to their re spective scanners when torch il is at M. Then the A motor is started in the manner to be described, and drives the torch along RII-N, and simultaneously moves the A scanners along their respective records; This action continues until a change in motion is required, as at point N. There it is required that the A motor stop and that the B motor start to execute N-P. This is done by a control mark n on the A-distance record 5t on the A drum, which is sensed by its scanner and operates suitable relays, to be described, to stop the A motor and to start the B motor.

The B motor now runs, moving the torch along N-P. It will be understood that now the A- records are stationary. At P, another change in motion is required, and a control mark p on the B-distance record 2l on the B drum actuates its scanner to stop the B motor and start the A motor. Itwill be clear that any desired gure having sides along the A and B directions may be executed in this manner, by alternating the operation ci the A and B motors.

From P to Q, however, a slant line is to be executed. This may be performed by a succession of steps, in which the treads represent incre mental displacements of the torch in the A direction and the risers correspond to increments in the B direction. Thus, if only two steps between P and Q are sulcient, as if only a crude approximation to the exact shape of the outline is required, the control mark p just described will start the A motor, which will run until the mark pi and point Pi. is reached'when the A. motor will stop and the B motor will start, running until maris p2 and point Pz is reached, when again the A motor is started, and runs to Bs. when it is stopped by mark pa, which then causes the E motor to run until point Q and marl. q are reached.

E desired, a larger number of smaller steps, as shown at d5, may be used.

in this manner any number of steps may be executed, resulting in as close an approximation to line P-Q asis desired. In actual practice, increments as small as als inch are being used. The serrations resulting from such small increments are eiectively smoothed by the action oi the torch, and the result appears as a substantially smooth straight line P-Q.

Up to the present point'. all motion, both in the A and the B directions, has been in the orward direction. .At Q, however, it is necessary to actuate the A motor in the reverse direction to es:- ecute @Q -R. This ls done by the second B rec I ord 28, termed the lll-reversing record. Just be fore the position of mark q on the B drum, a reversingcontrol mark q' is placed on the A-re versing record 28. This mark q is sensed by its scanner, and actuates a suitable reversing mechanism, as will be described, so that when mark d starts the A motor in the marmer already discussed, its direction of rotation will be in the opposite sense.

Such a reverse direction of rotation would normally reverse the motion o the A scanners relative to their drum, so that the scanners would travel from ps to p1 relative to the A drum, resulting in merely retracing the same outline M-N-P-Q, but in reverse sense, To avoid this,

the direction oi rotation of the drum relative to the motor must be reversed, so that, although the motor and torch reverse their direction oi motion,

the drum continues in the same direction and newl parts of the records become eiective instead of repeating the previous portions in reverse. This required, and no slipping at the clutch occurs, re-

sulting in a much simpler and .more effective and eicient system. Mark q is made as a strip rather than a spot, and maintains the reversed condition so long as the strip stays opposite its scanner.

The A motor is thus started, in the reverse di= rection, and torch ll traverses portion Q-R ci the outline while the A scanners continue in the same direction relative to the A drum. At R, mark r on the A record stops the A motor and starts the B motor. Since the B motor must ro tate reversely, a reversing-control strip mark 1" on the reversing record 5b, positioned ahead of spot mark r of the distance record 56, acts to condition the B motor to rotate in a reverse direction when energized by spot r. In a manner simaisance mark ri. All this time the A motor is maintained in reverse by control strip q. It is noted that strip q' may be formed as a series of marks each opposite one mark of the B-distance record, since in this way also the A motor can be maintained reversed, as required.

At Ri, mark r1 stops the B motor and starts the A motor, still in reverse, to execute 'R1-R2, until stopped by mark r2. This also starts the B motor, still in reverse because of control strip r, to execute R2-Ra- This process is repeated in similar fashion, until point Ra is reached.

At Re. control'mark re on the A-distance record 5ft starts the B motor. This is still in reverse, since the control strip r is still opposite its scanner. Hence the B motor executes Rte-R7, where control mark r1 stops it and starts the A-motor. Since the A motor must now rotate forwardly along Ril-Ra, the A reversing control strip q' is terminated before rv. It will be seen that this strip may end any time after rs.

Hence now the A motor will rotate forwardly along Rrr-Rs, until stopped by mark rs, which starts the B motor to execute Rs-Re. This is still in the reverse B direction, however. The same action continues therefore until the outline is closed at M.

If the entire outline is considered as executed by a succession of steps, each step comprising one increment of A motion and one of B motion, it will be seen that the ends of these steps are points P, Pz. Q, Ri, Ra, R5, Rv, R9. In the illustrative example used, some of these points, such as P, Pz, Q, fall directly on the required outline, while others (R1, R3, etc.) fall within the outline and still others (R1, Re) are outside the outline. Therefore, in laying out these steps, care must be taken to determine which points of the actual outline correspond exactly to points of the desired outline, in order to assure that these points be accurately located.

Also it will be noticed that for some parts of the traced outline, such as P-G and lts-M, excess area is left outside the desired outline, while for other sections (Rf-Rs) the internal area is reduced. In laying out the control marks. it is desirable to have all excess area outside, as when the outline of the steel plate is important, or to have all steps within the outline, as when a hole is to be cut, so that further fairing or adjustment may be simply made, as by grinding away excess material if a finer finish is desired or required. This may be easily done by suitable choice of the intermediate points of the curve. Thus, instead of proceeding along Q-R-Ri-Rz, this same curve may be executed along Q-R'R2, thereby changing from an internal step to an. external step.

In this manner, the torch l I may be automatically controlled to execute any desired outline or c urve, by alternate operation. of the two motors, each serving to stop itself and to start and reverse the other, under the control of their distance and reversal records.

Under some conditions it may be desired to stop the automatic traversal of the outline at predetermined points, as Where it is desired to indicate the exactA point at which a bulk-head is to be positioned. This may be done under the control of the stop records 29 and 56. Thus, if such a stop is required at point Pz, a stop control mark P2" is placed on the B control record 29, since that is the only record moving just beforePz. In the manner to be described with respect to Figs. 8A and 8B, this stops the torch without removing its control, so thatl tracing of the exact same outline by the torch may be resumed merely by properly restarting the apparatus.

If a stop is desired at point R4, for example. where the A motor is the last to run, the stop mark r4" is placed on the A stop record 58, as'

shown in Fig. 7.

At the end of the outline or curve. as at M if the curve is closed, stop marks mi" are placed on both the A and B records, and serve to completely disable the apparatus, to inform the operator that the cut is ended.

Referring now to Figs. 8A, 8B, and 8C there'is shown the complete wiring diagram of the automatic control system for the torch, in its deenergized condition, wherein all relay contacts are open except those designated by a diagonal line therethrough. Considering first motor A, providing the longitudinal motion of the cutting torch, it will be seen that motor A is adapted to be driven in a forward or reverse sense from a power source shown as a three-phase power line P1, according as its relay contacts A|-|, Al-2, AI3 or A2-|, A2-2, A2-3 are 'closed by their respective forward and reverse motor control relay coils Al or A2. A similar forward or reverse control of motor B producing the lateral or transverse motion of the torch is provided by contacts B||, BI-2, Bl-3 and B2|, B2-2, B23of the B motor control relays Bl and B2.

Upon starting the cutting operation. in which the torch is controlled from the records as described above, the switch |0| is thrown to its manual positiomM, vwhereby power is applied to the two lines L1 and L2. At the same timeall the clutch solenoids, namely the forward A clutch solenoid ACF, the reverse A clutch solenoid ACR, the forward B clutch solenoid BCF and the reverse B clutch solenoid BCR, are energized by the normally closed contacts AM-2 and AM-3 of relay AM, which is now deenergized, and the closed contacts AR-4 and BR--4 to be described.

Hence clutches 24 and 53 of Figures 1-3 are completely disengaged, and their respective drums are free from actuation by the A and B motors. These drums are now adjusted so that the initial points of their records are all opposite the corresponding scanners or pickups. Then the torch is adjusted to the initial point of the work at which cutting is to start; that it, to the point of the work corresponding to the setting of the drums just performed. This may be dcne by the proper actuation of the A and B forward and reverse manual control switches, such as the A- fcrward switch |02, the A-reverse switch |03, the B-forward switch |05 and the B-reverse switch |04, which respectively energize the relays Al, A2. Bi, and B2 controlling the 'motion of the A and B motors in these respective senses, by connecting these relays to lines L1 and La, now connected to source P2. In this way, the drums and torch are put into correspondence or register at the beginning of the cut. As will be seen, the drums and torch thereafter never leave register, until the vcut is completed.

After this initial adjustment is made, switch lill is thrown to its automatic position A. This disconnects line L2 from power source P2, and energizes the coil of relay AM, so that its contacts AM-I close and energize line La, and its contacts AM-2 and AM--3 open to energize only the A and B forward clutch solenolds ACP' and BCF through the normally closed contacts AR-I l1 and BR-I of the AR and BR relays to be described, whereby the drums will rotate in forward sense when their motors rotate forward.

The start switch I B is then closed, and energizes the A holding relay AH to close-its contacts AH-I and AH-2, and to open its contacts AH-S. Since contacts AS-I, SA-I and SB-i, to be later described, are normally closed, in the absence of energization of their respective relay coils AS, SA and SB, the closingof contacts AH-i closes a holding circuit which maintains relay AH energized even though the start switch |08 be released. Thus switch M36 may be of the momentary contact type.

The closing of contacts .AH-2 serves to energize the forward A relay AI through the normally closed contacts SB-i, AS-i, SA-Z,

AB-i and RA-i, and the normally closed forward A limit switch i'i. Switchitil provides means for interrupting the forward motion of the A motor in response to overtravel. in the well known manner, to increase safety of operation.

The opening of contacts Ali-ti isolates the plugging or braking circuit of motor A, to prevent undesired operaticn thereof. y The energization oi' relay Ai by contacts AH-2 serves to start the A motor in the forward direction, by closing contacts Ai-i, Ali-2, Ai-S, and thereby connecting motor A to line Pi for forward rotation. At the same time, ccntacts AI-t are opened. As will be seen, these contacts Ai-Q control the application of braking to motor A. Preferably relays Ai and A2 are a interlocked so that only one can operate at a time.

The forward rotation of the A motor and its control drum proceeds until'the A distance control scanner il (Fig. 8C); cooperating with .the A distance control record 54 on the A drum, senses a mark (corresponding to n of. Fig. 7), which preferably is in the form of a lightlrefiecting spot, by means of light reflected from a source |08 by this spot into the photocell H08. The current impulse thereby produced is amplified by a suitable ampliiier iii, which may be as shown in our copending application Serial No, 349.968, flied August 2, 1940, now Patent Number 2,336,- 376, dated December 7, 1943, and then actuates the A-stop relay AS, This energization of relay AS closes its contacts AS-2 and AS-3, and opens its contacts AS-l. It is to be noted that this energization will probably be only momentary, since the mark is of small dimensions, and the inertia of the system would tend to rotate the scanner past the mark before be'ng stopped.

The opening of contacts AS-i de-energizes the A holding relay AH, which drops out, thereby opening its contacts AH-i. AH-2, and closing its contacts AH-3. Since start switch |96 is no longer closed, it will be clear that relay AH will be kept de-energized, since its holding contacts AH-i are opened, even though contacts AS-i should again close.

The opening of contacts AS-i also de-energizes relay Ai, with Whose circuit thesecontacts are in series. so that relay AI drops out and de-energizes motor A. The opening of contacts AH-Z in series with contacts AS-i assures that this circuit will be kept open even though relay AS should not stay energized, due to the scanner moving past the control mark. Contacts AH-2 thus insure that relay Ai remains de-energized thereafter.

The reclosing of contacts AH-3 places the plugging' switch H2 in circuit with the energiza tion of motor A. under the control of contacts AI-ll. Switch H 2 is responsive to rotation of motor A, and, for a forward rotation of motor A,

closes its upper contacts so long as the motor continues to rotate above a predetermined speed. This switch may be of the type commercially known as the General Electric plugging switch type CR 2962A. Hence, after relay Ai has been de-energized, reclosing its contacts Ali-3, energy is supplied to relay A2, which thereby impresses reverse power on motor A. so as to brake the motor to a standstill. As the motor reaches low speed switch M2 falls out, whereby relay A? is de-energized and reverse rotation of the motor is prevented, so that the motor stops practically dead. Contacts AI-ii prevent operation of relay A2 until after relay Ai has opened.

The momentary energization of relay AS also closes its contacts AS-2, thereby energizing the B forward motor control relay Bi through normally closed contacts SB-i and SA-i, the closed contacts AS-2, normally closed contacts Sii- 2, AB-S and RB-i and the normally closed B-forward stop switch H3. It will be clear that switch H3 provides means for manually interrupting the energlzation of relay Bl and hence the forward motion of motor B whenever desired.

The energzation of the B forward motor control relay Bi serves to start the forward rotation of the B motor by closing contacts Blf-i, Bi-il, Bi-3. Also contacts Bi-d, similar in function to lil-l, are opened, disabling the B reverse motor control relay B2 insofar as the plugging circuit is concerned.

However, as discussed above, the energization of relay AS and yhence the closing of contacts AS-2 may be only momentary. To insure proper operation ci the system, the closing of contacts AS-S energizes the B holding relay BH through contacts SB-i and AS-3, thereby closing its contacts BH--i and 13H-2, and opening con= tacts BH-3,

Contacts BH-I serve as a holding circuit to maintain relay BH energized despite de-energization of amplifier-operated relay AS. Contacts BHI-2 serve as a holding circuit for relay Bi to insure continued rotation of the B motor. Contacts BH-3 open to further isolate the B motor plugging circuit.

In this manner, the A motor is rapidly stopped, and the B motor starts to drive the ame cutter ln a perpendicular direction to provide a further increment to the desired outline or curve.

Rotation of the B motor also drives the B drum in a forward direction. This operation continues until a control mark on the B-distance control record S9 on the B drum is intercepted by the corresponding scanner, whereupon the B- stop relay BS is energized, at least momentarily. to close its rcontacts BS-2 and BS- and to open contacts BS-i.

The function of the B-stop relay BS is similar to that of the A-stop relay AS. In brief, the B- forward motor control relay BI is de-energized, and the B plugging circuit is conditioned to be operated by the B plugging switch lili, similar to switch H2, to instantly stop the B motor. In addition, the B holding ,relay BH is deenergized to fall out and to keep the Bi relay de-energized even after relay BS falls out. Also, the BS relay energizes the A holding relay AH and the A forward motor control relay Ai to initiate and main.. tain forward rotation of the motor. The action is entirely similar to that of the corresponding A relay AS, merely reversing the A and B roles.

In this manner the A and B motors automatically alternate operation, each running for a period dened by the interval between marks on the distance record of its corresponding drum, but the starting of each of these periods being controlled by the record of the opposite drum. Thus, the starting oi.' each motor is initiated by a mark on the opposite drum record, and each motor is stopped by a mark on its own drum record.

As thus far described, the A and B motors operate alternately to execute the desired curve of the outline, in the forward direction. For reversing the direction of the motors, the respective drums are each provided with a second or reversing control record, and a corresponding photoelectric pickup or scanner unit, as described above. These are similar to unit H0, and are in- 'dicated schematically in Fig. 8C by the dotted lines i2l, |22.

In the above description, it has been tacitly assumed that the retrace switch |23, whose function will be described below, was in the forward position. as shown, so that relays RA and RB were de-energized. Let it be further assumed that one motor, such as the A motor, is operating, and that the next operation oi the B motor is to be in the reverse direction. Then, just before the A-stop control mark on the A drum actuates relay AS to stop the A motor and start the B motor, in the manner already described, a B reversing control mark (corresponding to strip'r in Fig. 7) also on the-A drum, but on the reversing control record B5 thereof, energizes the B reversing control relay BR, through the action o1' its corresponding scanner. `This closes contacts BRf-I and BRI-3, and opens BR-2 and BR-4.

Contacts BR-l energize the B reversing relay RB through the now closed contacts AM-i, and thereby closes its contacts RB-2 and opens contacts RB---L` In this way the B reverse motor control relay B2 is conditioned to be subsequently operated by the A-stop B-start relay AS, while the B forward motor control relay BI is disabled. Accordingly, upon subsequent stopping oi the A motor and starting of the B motor, .the'B motor will rotate in reverse sense from its previous rotation.

Since the drums and motors are directly geared together to rotate in synchronism, it will be seen that reversal oi the direction of rotation of a motor would also reverse the direction of rotation of the corresponding. drum, so that the records on the drum would be repeated by traversal in reverse sense. This would merely cause the torch to traverse the same increments but in reverse order, no matter what the other motor was doing. To prevent this, it is necessary to reverse the relative directions of rotation of thev motor and drum. so that the drum will continue to rotate in the same direction even though the motor has reversed. This is done, in the present illustration, by actuation o1' the BR relay, which closes its contacts BR-B and opens BR-t, thereby cie-energizing the B forward clutch solenoid BCF and energizing the B reverse clutch 14 being reversed is at standstill. thus avoiding the necessity of reversing a moving system with its consequent complexities of power and kinetic energy control. Also, accurate registration between drum and torch is maintained by clutching only at standstill, when no slipping can occur.

Contacts BR-2 are ineffective to produce any result in the illustration used, but become usefui when switch |23 is thrown to the retrace posion, as will be described.

Since relay BR will remain energized only so long,1 as a reversing mark is sensed by the B reversing scanner, it will be clear that this mark v may be in the form of a line extending in the dithe B drum, which operated through its scanner solenoid BCR to reverse the direction of rotato actuate the A-reversing control relay AR to control the motor reversing relay RA, and thus replace the relay AI by the relay A2, and also to actuate the clutch solenoids ACF and ACR to reverse the drum rotation relative to the motor rotation.

In the above manner the A and B motors may be automatically controlled by their respective drum records to execute any desired curve or outline. By making the intervals of operation of each motor rather short, it is possible to have the cutter describe very complicated and intricate outlines with a high degree of fidelity, even though microscopically the actual path of the cutter would be yseen to be zig-zag.

Under some conditions, as for example when the flame has gone out without being noticed, or for other reasons. it may be desirable to have the torch retrace the 'same path. This may be done simply by throwing retrace switch |23 to its retrace position. This energizes both relays RA and RB through AR2 and BR-2 now closed and thereby serves to effectively interchange relays AI and A2,' and relays BI and B2, so that whichever motor is operating will be run in the reverse direction. Sinc the drum clutches are not ailected, the drums as Well as the torch will be operated in reverse. Thus, for example, referring to Figures 5 to '7, if the retrace switch |23 were actuated when the torch is between R and Q, the torch would at once return toward Q. At the same time, the A scanners would be moving to the left in Figure 7, instead of to the right as formerly. At p3 the B starting action described above would occur, and the Almotor would stop. Since relay RB is now energized by switch |23, contacts RB-2 are closed and contacts RB-I open, so that the B motor will operate in reverse, along QPz. Now the torch goes along Q-Pa, and the B scanners traverse the B records upwards in Figure 6, instead of downwards as before, from q to p2. In so doing, the A reversal scanner on the B 'drum leaves the control strip mark q', thereby de-energizing relay AR to reverse the A-drum drive, and energizing relay RA to reverse the A motor direction upon its operation in response to mark p2.

During normal operation of the device, the scanner will travel past the distance control mark before stopping. Accordingly, when retracing, the scanner will be actuated by the same control mark, and will improperly interchange A and B directions of motion at the beginning of retracmotor.

actuation of switch |24.

ing. 'To prevent this, the drums may be rotated slightly by hand before beginning retracing, by the amount necessary to put the scanners on the other side of the control mark last reached.

In some operations it may be desirable to stop the torch at predetermined points of the outline, as for the purpose of placing or punching marks on the work to indicate special points, as points where bulkhcads, etc., are to be placed. If the master power switch or any of the manual stop switches were opened at such points, the system might restart thereafter with the wrong motor operating, or on the wrong foot. To prevent this, and to automatically stop at the required point so that the operator can have no opportunity to overlook the marking point, a third or punch-stop record is placed on each of the A and B drums, as shown at 29 and 5S in Figures and 6, cooperating with respective scanners indicated schematically in Figure 8B.

Assuming for example that the A motor is operating, the control mark on the A punch-stop record, such as r4 of Figure 7 will actuate the punch-stop relay SA, thereby closing its contacts SA-3 and opening SA--l and SA-2. Contacts SA-2 disable both the A motor control relays A1 and A2, so as to prevent the energization of either one. Contacts SA-3 energize the stop holding relay AB, which, through its contacts AB-4, holds itself energized, the manual restart switch |24 being normally closed.

Relay AB also closes its contacts AB-2 and opens AB--I and AB-3. Contacts AB-3 are4 in series with SB-2, and serve to maintain the B motor inactive, even though the SB relay should not stay energized, as might occur because of inertia in the system permitting the scanner to overrun the control mark. Contacts AB-l serve to de-energize the A motor, no matter what its direction of rotation, being in the common lead for both the Ai and the A2 relays controlling both directions of rotation of the A motor.

At the same time, contacts AB-2 serve to apply plugging to the A motor through contacts BH-3, AB-2, switch H2 and the proper contacts A|4 or .A2- 4, depending on which of relays Al or A2 is energized to rotate the A motor. As soon as the A motor is stopped, both motors remain stopped, since the plugging circuit is no.

longer effective to apply power to the A motor, which isy otherwise open-circuited by AB-i, and since motor B is open-circuited by AB3.

If the B motor were running, a control mark such as p2" on its punch-stop record in Fig. 6 would operate its stop relay SB to energize relay AB, which would act as already described to disable the stationary A motor to prevent its possible energization, and to stop the rotating B Contacts A1B-2 will be seen to operate the plugging for both motors, since at least one of contacts AH-3 or BH-S willalways be closed, in accordance with the particular motor which is rotating.

To restart the system after being thus stopped, manual restart switch |24 must be actuated, which de-energizes the AB relay, .and permits the system to resume operations at the point where it left off when stopped. That is, the same motor will again start and in the same direction, since the holding relay AH or BH corresponding to the motor operating when stopped, has remained energized. In this way, the motion of the torch is automatically stopped at the proper point, and the attention of the operator is at once attracted, since the system caribe restarted only by manual 1f it is desired to stop the machine completely, as at the end of the cut, end-stop marks mi" (Figs. 6 and 7) serve to energize both relays SA and SB to stop both motors. Moreover, at this time the restart switch |24 is no longer effective to restart the machine, since both holding relays AH and BH remain opened and completely disable both motors.

If it is desired to manually stop the system and in a manner to -permit resumption of the same outline, as when the torch goes out, for example, stop switch E25 may be actuated to energize relay AB, which will then operate to stop the system in the manner described, no matter which motor is operating or in which direction the motor is rotating. The system may be restarted as before by switch |26,

It will be noted that. during manual control, when switch IGI is in its manual position M, relay AB remains energized. This operates to open its contacts A1B-l and AB-3, so as to isolate the system against indirect energization of the motor control relays through other relay contacts.

Thus far it has been tacitly assumed that the proper control records exist, without discussing the manner in which these records may be produced. Of course, the records could be made by hand from a knowledge of the required outline and the proper computations, in accordance with the discussion relative to Figs. 5 to 7. Preferably, a diiierent and simpler method, usable by any operator without excessive instruction, is employed. For this purpose, apparatus is provided for manually controlling the A and B motors, whereby the torch or an index member substituted therefor may be manually controlled to execute the outline or curve. A template is made up, bearing the desired outline, or the outline is drawn on a plate or on the door, and the motors are controlled in such manner that the torch or index member traces the template or drawn outline. At each point Where a change in the direction of the torch is required, a proper mark is placed-on the correct drum record which is actuated synchronously and in register with the .corresponding motor. Such a mark may be placed manually after stopping the motion of the index, or may be made by a suitable controlled scriber, as shown in our copending application Serial No. 349,968, filed August 2, 1940, now Patent Number 2,336,37 6, dated December '7, 1943.

It is noted that for straight slanted portions of the outline, such as P-Q, or curved portions such as R-M, it is not necessary to trace the entire curve by the index, making rec-ord marks at each change, Rather, for straight portions such as P-Q it is merely necessary to place the index at point P and mark the proper drum at that point, and repeat at point Q. Then the drums may be completed after removal from the machine by adding the further necessary marks by dividing the record intervals corresponding to P-Q into a number of equal parts corresponding to the desired number of steps, a mark being placed at each of these subdivisions on each of the records.

Curved portions such at R--M may be resolved into a number of essentially straight portions such as R-Rz, R2, R4, etc., the number of por- .so that the required accuracy of tracing of the outline could be maintained. In effect, the curve said control indicia.

said second direction, photoelectric pick-up means cooperating with said iirst record for stopping said first motive means and starting said second motive means under the control of said first control indicia, and photoelectric pickup means cooperating with said second record for stopping said second motive means and starting said iirst motive means under the control of said second control indicia, whereby said tool is operated.y in steps to execute an outline corresponding to both 2. Apparatus as in claim 1, further comprising a second set oi control indicia on each of said records, and photoelectric pickup means cooperating with each of said second sets of indicia for reversing the direction of motion oi' the motive means corresponding to the other of said second sets of indicia while maintaining unchanged the direction of motion of the record corresponding to said other set, whereby said tool may execute a curve having both forward and reverse increments of motion along said two directions.

3. Apparatus as in claim 1, further comprising a further set of control indicia on 'each of said records, photoelectric pickup means cooperating4 with each of said further indicia for stopping both said motive means under the control of either of said further sets of indicia, and manual means for controlling resumption of operation of said motive means without aecting the synchronism oi' said motive means with their respective control indicia, whereby said apparatus may be automatically stopped by said further indicia at a point of said outline corresponding to the position of either of said further indicia on their respective records.

4. Apparatus as in claim 1, further comprising a second set of control indicia on each of said records, photoelectric pickup means cooperating with and controlled by each of said second sets of indicia for reversing the direction of motion of the motive means corresponding to the other of said sets while' maintaining unchanged the direction of motion of the record bearing said other set, whereby said tool may execute a curve having both forward and reverse increments of motion along said predetermined directions, a third set of control indicia placed on each of said records, photoelectric pickup means cooperating with and controlled by each of said third sets for stopping both of said motive means, and manual means for controlling resumption' of operation of said motive means without affecting the synchronism of said motive means with their respective records, whereby said apparatus may be automatically stopped by said third sets of indicia at points of said outline corresponding to the location of said third sets on their respective records.

5. Record-controlled curve-tracing apparatus comprising a tracing member, motive means for driving said member in a predetermined direction, a control record driven by said motive means synchronously with said member, a second motive means for driving said member in a second independent predetermined direction, a second control record driven by said second motive means synchronously with the motion of said member along said second direction, said rst record bearing control indicia having successive spacings corresponding to desired increments of motion of saidmember along said rst direction, and said second control record bearing control indicia having successive spacings corresponding to desired increments oi' motion of said member along said second direction. means cooperating with said iirst record for stopping said rst motive means and starting said second motive means under the control of said first control indicia, and means cooperating with said second record for stopping said second motive means and starting said first motive means under the control of said second control indicia, whereby said member is operated in steps to execute an outline corresponding to both said control indicia.

6. Record-controlled curve-tracing apparatus comprising a movable member, motive means for independently driving said member along a plurality of predetermined coordinates, respective control records driven by said motive means synchronously with said member and bearing indicia respectively corresponding to desired increments of motion of said member along said predetermined coordinates, and means controlled -by said indicia for controlling said motive means to drive said member successively and periodically along said coordinates by increments corresponding to said indicia, whereby said member is operated in steps to trace a curve corresponding to said indicia.

7. Apparatus as in claim 6, further comprising further indicia carried by' said records, and means controlled by said further indicia for reversing the direction of motion of said member along a respective coordinate While maintaining the same direction of motion of said records.

8. The method of tracing a curve having predetermined increments along two independent directions comprising the steps of preparing a pair of control records bearing indicia successively spaced in correspondence with said increments along respective directions, and alternately moving a. tracing member along said respective directions by increments corresponding to the spacing of the indicia o n respective records.

9. A device for executing a desired pattern comprising a movable member, a iirst motor for moving said member along a rst rectilinear path, a second motor for moving said member along a second rectilinear path at a right angle to said rst path, a rst control member driven by said iirst motor and having indicia thereon, a second control member driven by said second motor having indicia thereon, detecting means associated with each of said control members for sensing the indicia thereon, and means electrically connecting the detecting means associated with said first control member with said rst and second motors for stopping said iirst motor and starting said second motor when an indicium is sensed on said iirst control member, and means electrically connecting the detecting means associated with said second control means with said second and said rst motors for stopping said second motor and starting said rst motor when an indicium on said second control member is sensed.

10. A device for executing a desired pattern, comprising a movable member, first means for moving said member along a rst path, second means for moving said member along a second path at an angle to said iirst path, rst control means actuated by said iirst means for stopping/said rst means and starting said second means, and second control means actuated by said second means for stopping said second means and starting said rst means.

11. Adevice for executing a desired pattern, comprising a movable member, rst means for moving said member along a rst path, second means for moving said member along a second path at an angle to said first path, rst, control 21 means actuated by said first means and having controlindicia for stopping said rst means and starting? said second means, and second control means actuated by said second means and having control indicia for stopping said second means and starting said first means.

12. A device for executing a desired pattern comprising a movable member, a first motor for moving said member along a first path., a second motor for moving said member along a second path at an angle to said first path, a first control member actuated by said first motor and having indicia thereon, a second control member actuated by said second motor and having indicia thereon, and indicia detecting means connected with said first and second motors for (i) stoppins said nrst motor and starting said second motor upon detection oi an indiciuin on said first control member and i2) ior stopping said sec-s ond motor and starting said iirst motor upon detection of an indicium on said secondcontrol monito iii.. it device for executing a desired pattern comprising a movable member, a i-lrst reversible rector tor rnoving'said member alongI a path,

for stoppin@ said second motor and starting' tiret motor upon detection oi an indicinrn on said second control member, and additional detecting oceans connected with oaioi motors for ciontroilins the direction oi' operation oi saidino= toro icy detection oi indicia on said control mero@ L isere it. il device ior executing a desired pattern, comprising a. movable member, a first reversible motor for moving said member alone a first path, a second reversible motor for driving said inemiier alone a second path at en ans-le to said niet path. a first movable control member having indicio. thereon driven by said first motor, means responsive to indicia on said iirst control memloer icr stopping said first motor and starting said second motor in a forward or reverse direc tion, a second movable control member having? indicia thereon driven by said second motor, means responsive to indicia on said second con llt trol member for stopping said second motor and starting said nrst motor in a forward or reverse direction, and reversible transmission means between said motors and their respective control members for rotating said control members in one direction, regardless oi' the direction of rotation oi said motors.

l5. A device for executing a desired pattern, comprising a movable member, a first reversible motor for moving said member along a first path, a second reversible `motor for driving said meinber along a second path at an angle to said first path, a rst movable control member driven by said iirst motor and having control indicia thereon, photo-electric cell means responsive to indieia on said iirst control member for stopping said lrst rnotor and starting said second motor inge. forward or reverse direction, a second movable control :member driven by said second :motor and having indicia thereon, photo-electric cell means responsive to indicia on said second control member ior stopping said second motor and starting said first motor in a forward or reverse direction, and reversible transmission ineens between said motors and their respective control members for rotating said control niem-s ers in one direction, regardless of the direction of rotation of said motors..

iiie this STATES -3 itnniher Namo Dato @21H82 Elliott ...s June i2, M394 1,653,927 Kreise ...s Feb. ifi, 192e ltotl .'i-iotvev s nos'. 22, i933 iiiiilii Wilkins et ai. Feb. o, i934, i,o74,5i3 Sciieidhauer iiept. 25, 193e 2,il29,335 beriiolilren et al. u.. o, i938 2,08%@14 Bocknaro Aus". S, 193'! ootozl Watson Aug. lil, 193? 2,172,313 Young s Sept. o, 1939 @21H66 Pollard, Jr. Aug, 27, 194e 2,238,082 Somos -s Apr. 15, i941 2,261,644 Cocirrell Nov fi, 1941 2,236,571 Pollard June 18, 1942 FOREIGN @MENTS Number Country Date 513,848 Great Britain ct. 24, 1939- were 

